The present invention relates to a method of position determination as well as a system for using the method and determining the position of a transmitter/receiver device arranged anywhere in a space in relation to at least two transmitter/receiver devices arranged at defined positions with regard to each other in the space. In addition, the present invention relates to a transmitter/receiver device for a position determination system.
Methods of and devices for position determination, in which a directional or loop antenna is used and positioning takes place by way of orientation of the antenna towards a transmitter in dependence on the maximum received signal, are sufficiently familiar. With such methods or devices it is, however, necessary for a device to be provided, which carries out orientation or guiding of the directional antenna depending on the field strength of the received signal. As a result of the required mechanical equipment, such devices are not generally suitable for miniaturization.
In divergence from the aforementioned devices, which can still be implemented with relatively little apparatus, so-called xe2x80x9csatellite positioning systemsxe2x80x9d are also known, which under the name of xe2x80x9cGlobal Positioning Systemsxe2x80x9d (GPS) have now found their way into everyday applications, such as vehicle navigation systems.
However, these systems are characterized by enormous equipment requirements. Furthermore, GPS position determination systems are often not suitable for determining the position in enclosed spaces, in particular rooms with solid walls, such as concrete buildings or underground buildings.
U.S. Pat. No. 5,574,468 (Rose) discloses a system for determining the position of a target including a plurality of antennas in a phase comparison interferometer array, arranged in a conformal manner such that measurements are determined using a group of different baseline antennas. This kind of interferometer only operates in the emitters far field.
U.S. Pat. No. 5,045,860 (Hodson) discloses a system for determining position of a target in a target area with a plurality of fixed signal sensing stations, which are calibrated in reference to a reference direction, for example true or magnetic north, The object is determined by the intersection of the lines of bearing (LOB) within the target area. To minimize error the target area is divided into a grid of target area segments, whereby to each target area segment a partial probability value of a statistical error model is assigned.
U.S. Pat. No. 4,728,959 (Maloney) discloses a direction finding localization system for mobile radio transmitter within cellular telephone system with a number of fixed stations. The angle of arrival of the signal is measured at the fixed stations and the area in which all the direction angles cross is determined. The direction angle is determined by comparison of the difference in phase of the radio signal that is received by different antenna elements at a receiver site and is related to a reference direction.
U.S. Pat. No. 3,953,131 (Britz) discloses an optoelectronic antenna system with a plurality of transmitter/receiving devices, which are disposed over a prescribed geometrical surface, there are detectors coupled to the transmitter/receiving devices via glass fibre. Thus three-dimensional space scanning operations are possible. The antennas show different apertures depending on the position of the antenna. Thus the antenna system must be aligned to the earth gravitation field.
The aim of the present invention is to propose a method and a device suitable for implementing the method, allowing inertial system independent position determination with minimal requirements that can be easily miniaturized and is also usable within enclosed spaces.
The aim is realized by a method with the features including the procedural steps:
definition of a local co-ordinate space through the arrangement of at least two transmitter/receiver devices with a number of antenna units, arranged with a defined distribution on a spherical surface of the transmitter/receiver devices, in a space, in such a way that the transmitter/receiver devices are in defined relative positions at known horizontal and vertical distances,
emission of a signal S1 via the antenna units of the first transmitter/receiver device and receiving of the signal S1 via the antenna units of the second transmitter/receiver device, determination of the distance vector between the first transmitter/receiver device and the second transmitter/receiver device through determining the antenna unit of the second transmitter/receiver device with the maximum receiving strength of the signal and emission of a signal S2 via the antenna units of the second transmitter/receiver device and receiving of the signal S2 via the antenna units of the first transmitter/receiver device as well as determination of the distance vector between the second transmitter/receiver device and the first transmitter/receiver device through determining the antenna unit of the first transmitter/receiver device with the maximum receiving strength of the signal,
position determination of a third transmitter/receiver device arranged anywhere in the local co-ordinate space through emission of a signal S3 via the antenna units of the third transmitter/receiver device and receiving of the signal S3 via the antenna units of the first and second transmitter/receiver devices, determination of the antenna units of the first and second transmitter/receiver devices with the maximum receiving strength of the signal, determining the direction vectors between the first and the third transmitter/receiver device and the second and the third transmitter/receiver device, as well as determining the intersection of the direction vectors for determining the position of the third transmitter/receiver device.
The position determination system in accordance with the invention is for determining the position of a transmitter/receiver device arranged anywhere in a space in relation to at least two transmitter/receiver devices arranged at defined positions in the space with regard to each other. The system comprises at least three transmitter/receiver devices, with the transmitter/receiver devices each having an antenna system with a number of antenna units arranged with a defined distribution on a spherical surface and a signal generating device, with two transmitter/receiver devices being at least temporarily fixed in a local co-ordinate space and the other transmitter/receiver device being movable relative to the devices.
To construct the system a transmitter/receiver device may be used with a carrier device for arranging a number of antenna units of an antenna device on a spherical surface, a signal generating device and a processor device, whereby the signal generating device generates signals in dependence on the processor device, and the processor device through comparing the receiving strengths of the signals can determine the antenna unit of the antenna device with the maximum receiving strength.
The method of position determination according to the invention permits the inertial system-independent definition of a local co-ordinate system through two transmitter/receiver devices and the spatial position determination of a third transmitter/receiver device within the local co-ordinate space. In this way an exact position determination independent of an external system is possible, so that there are no limitations in the implementation of the method, as are present and have already been described in the case of the GPS.
As the method in accordance with the invention dispenses with the orientation of an antenna unit to a maximum signal strength, and instead uses a number of antenna units arranged on a spherical surface for defining a position signal, in that the antenna unit with the maximum receiving signal is detected, a simple and unchanged arrangement of the antenna units can be selected, whereby the mechanical structure of the system and the relevant transmitter/receiver device is considerably simplified and miniaturization can be easily carried out.
Various embodiments are conceivable for the transmitter/receiver devices used in the position determination system, depending on whether it is sufficient only to determine the position of a third transmitter/receiver device with regard to two transmitter/receiver devices arranged in a fixed manner in a space, or whether the third transmitter/receiver device is formed as an active mobile transmitter/receiver device, which actively determines the current position in order to be able to calculate a traveled path.
The method according to the invention, as well as a suitable system for implementing the method according to the invention using suitable transmitter/receiver devices, will be described in more detail below with the aid of the drawings.